Field of the Invention
The present invention relates, in general, to an injection mold for rotary-type gravity casting and a gravity casting method using the same and, more particularly, to an injection mold for rotary-type gravity casting which prevents the ingress of impurities into the mold during the gravity casting accompanied by rotation, and a gravity casting method using the same.
Description of the Related Art
Generally, gravity castings are casting processes that fabricate castings, such as pistons, sleeves, crankcases, cylinder heads or the like, by pouring a molten material, such as nonferrous alloy including aluminum (Al), magnesium (Mg), copper (Cu) or the like, cast iron, or steel, into a mold using gravity. Currently, when a cylinder head for a diesel engine is manufactured using the gravity casting, a riser is used to store molten metal used to compensate for the shrinkage of the casting, thereby providing a high quality of product.
Particularly, the riser provides the casting with a final solidified part to allow the casting defects and impurities to be collected therein, as well as to provide latent heat required for the casting to be uniformly unidirectionally solidified. A molten metal recovery ratio can be expressed by a ratio of product weight to total amounts of molten metal injected, and thus research and development of the technology for improving the quality of the casting while reducing the size and number of risers has been actively performed.
However, in the manufacture of a conventional cylinder head, as shown in FIG. 1, risers occupy about 50% of the total volume of molten metal injected, thus causing the recovery ratio to be a mere 50%. Further, rectangular injection molds are used to introduce molten metal into the mold along with impurities, degrading the quality of the casting.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.